Information technology and the computer industry are highly developed now. Portable electronic devices, such as a notebook computer, are widely used. Due to weight and practical requirements, portable devices tend to be lighter, thinner, shorter and smaller. The notebook computer is a successful product because the notebook computer with powerful calculation capability deals with a great amount of digital data.
The semiconductor manufacture process has highly progressed. The design of the semiconductor becomes more complicated and more sophisticated on a daily basis due to functional requirements. For example, the electric circuit layout of the central processing unit (CPU) is more complicated because the CPU has to provide enough functions for users and application software. The new generation CPU provides powerful functions and performance but the powerful CPU generates some new problem in use. A serious problem is that the new CPU with a complicated circuit has a higher power consumption and thus severely elevates the temperature of the chips. The high temperature can cause instability in the working system, and especially in a small-sized portable device. In general, a lower work temperature makes a portable device more stable. That is to say, if the notebook computer temperature can be lower, the performance thereof is higher. If the temperature is high, the performance and stability decrease, and the operation system may even crash.
In practice, the notebook computer needs a high powered fan to exhaust internal heat. The high power fan is loud while it is working. The noise comes from not only the fan itself but also the quantity of the magnetic poles, revolutions, blades of the fan, and combinations thereof.
FIG. 1A is a heat dissipation apparatus of a traditional notebook computer. The cooling apparatus includes a heat sink 110, a heat pipe 120, a fan 130, and heat exhausting fins 140. The heat sink 110 collects the heat energy generated from the central processing unit (CPU) of the notebook computer and the heat pipe 120 delivers the heat energy to the heat exhausting fins 140. Then, the fan 130 blows on the heat exhausting fins 140 to carry the heat energy out of the notebook computer.
FIG. 1B shows airflow directions of FIG. 1A. The arrows 150 show the airflows direction inside the fan 130. As the drawing shows, the airflow caused by the rotating fan has directions nearly perpendicular to a line from the center to the contact point on the blade of the fan 130. When the airflow contacts the heat exhausting fins 140, the airflow direction follows the direction of the heat exhausting fins 140. Therefore, angles between the airflow direction, arrows 150, and the heat exhausting fins 140 vary in different positions relative to the fan 130 and the heat exhausting fins 140. When the angle is larger, the exhausting volume is lower and the noise is caused by turbulence in the heat exhausting fins 140 is more serious. Arrow 160 shows volumes of airflow exiting the heat exhausting fins 140. The length of the arrow 160 indicates airflow volume. Therefore, the airflow volume distribution and noise sources are clear.
A high proximity between a notebook computer and a user thereof means that any obvious noise causes the user discomfort. Product image is correspondingly diminished. A quieter cooling apparatus for a notebook computer favors the user and is immediately perceived by the user. Hence, a quieter cooling apparatus makes the notebook computer more comfortable and practical as well as greatly enhancing the product image thereof.